JPH06292092A - Image pickup device - Google Patents

Abstract

PURPOSE:To obtain an image pickup picture without a shake and with high resolution even when a motion of an object is fast by letting substantial exposure time by the portion of one picture be a specific field when a picture is shifted. CONSTITUTION:Since an image pickup light in the horizontal direction made incident on a liquid crystal display panel 2 via a 1st polarized light plate 1 transmits through the plate 2 at the time when a voltage applied to the 1st liquid crystal display plate 2 is ON as it is, the light does not transmit through the 2nd polarized plate 3 whose polarized light direction is the vertical direction. Thus, no image pickup light is emitted to a CCD image sensor 10. The image pickup light in the horizontal direction made incident in the liquid crystal display plate 2 via the polarized light plate 1 is made incident on the 2nd polarized light plate 3 as an image pickup light in the vertical direction by the liquid crystal display plate 2 at the time when the voltage to the plate 2 is OFF and transmits through the polarized light plate 3 and is made incident on the 2nd liquid crystal display plate 4. Since the voltage is not applied to the liquid crystal display plate 4 in one frame period, the polarized light direction of the image pickup light in the vertical direction is set in the horizontal direction and made incident on the quartz crystal display plate 7 via an IR filter 6. The quartz crystal display plate 7 does not shift the optical path for the image pickup light in the horizontal direction but radiates on a sensor 10 via a phase difference plate 8 and an optical LPF 9 as an ordianry light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a solid-state image sensor (CCD).
The present invention relates to an image pickup device suitable for use in a video camera device or an image scanner for picking up an image of a subject using an image pickup device such as an image sensor) or a pick-up tube. The present invention relates to an image pickup device which picks up an image while electrically shifting a relative position to the image pickup light, and which shortens an exposure time when the image pickup means is used for frame reading.

[0002]

2. Description of the Related Art Solid-state image sensor (CCD image sensor)
Has been widely used in video camera devices, image scanners, and the like because of its small size and low power consumption. Although the video camera device or the like is usually provided with a CCD image sensor of about 400,000 pixels, the CCD image sensor of about 400,000 pixels has a considerably lower resolution than an image pickup tube.

In recent years, high-resolution television receivers called so-called high-definition television receivers (HD television receivers) have become widespread.
In order to support this HD television receiver, a CCD image sensor having a reduced pixel area and an increased number of pixels of 2 million has been developed.

However, if the pixel area is reduced, the level of the image pickup signal output from the solid-state image pickup device is lowered, and the S / N ratio is lowered. Considering this decrease in S / N ratio, the solid-state image pickup device with 2 million pixels is almost at its limit, and it is currently difficult to further increase the number of pixels to improve the resolution. In addition, the above 20
Even with a CCD image sensor of 0,000 pixels, the resolution is still insufficient to be used for inputting a print document or the like, and higher resolution is required.

For these reasons, solid-state image pickup devices (CCDs)
It is possible to increase the resolution without increasing the number of pixels by increasing the spatial sampling area by shifting the relative position between the image sensor) and the image pickup light by an integer of 1 or more of the pixel pitch. An imaging device capable of being developed has been developed.

In this image pickup device, a CCD image sensor is provided on a piezoelectric element, and the CCD image sensor is halved.
By oscillating in one direction for each field with the amplitude of the pixel pitch, the image pickup light with which the CCD image sensor is irradiated is divided into 1/2 pixel pitches and is irradiated (image shift)
Therefore, it is possible to obtain a high-resolution image without increasing the number of pixels by increasing the spatial sampling area.

In addition, there is also known an image pickup device in which a thin glass plate is provided in front of a CCD image sensor and an image is picked up while vibrating the glass plate at a minute angle. This image pickup device uses the CCD every time the glass plate is vibrated.
The image pickup light applied to the image sensor is subjected to the image shift, so that the spatial sampling area can be increased and a high-resolution image can be obtained without increasing the number of pixels.

However, such an image pickup device irradiates the CCD image sensor with mechanical vibration such as vibrating the CCD image sensor itself or vibrating a glass plate provided in front of the CCD image sensor. Since the light is image-shifted, the mechanical structure is complicated and the image shift itself is poor in reliability.

Therefore, in order to correct such a defect of the image pickup device which mechanically performs image shift, an image pickup device which can electrically perform the image shift has been developed.

The image pickup device for electrically performing the image shift is, for example, between a CCD image sensor and a lens,
A quartz plate is provided as an optical element exhibiting a so-called birefringence phenomenon. Further, a liquid crystal plate, which is turned on and off by a voltage and has a polarizing film attached thereto, which is turned on and off by a voltage and transmits only imaging light having a horizontal (H) direction (hereinafter, simply referred to as “imaging light in the H direction”), is attached to the crystal plate. Is provided.

In such an image pickup device, image pickup light whose polarization direction is the H direction is incident on the liquid crystal plate through the polarizing film. An alternating voltage is applied to the liquid crystal plate, for example, for each field. When the AC voltage is applied, the liquid crystal plate emits the incident imaging light in the H direction as it is without converting the polarization direction, and when the AC voltage is not applied, the imaging light in the H direction is emitted at 90 degrees. The polarized light having a polarization angle difference is converted into imaging light in the vertical (V) direction (hereinafter, simply referred to as imaging light in the V direction) and emitted. The image pickup light in the H direction and the image pickup light in the V direction emitted from the liquid crystal plate are
Each is incident on the crystal plate.

When the image pickup light in the H direction is incident, the crystal plate irradiates the CCD image sensor as ordinary light without changing its optical path, and when the image pickup light in the V direction is incident, the H light is emitted. The optical path of the imaging light in
For example, a 1/2 pixel pitch is shifted downward in the V direction, and the CCD image sensor is irradiated with this as abnormal light.

That is, as the imaging light emitted to the CCD image sensor, the ordinary light and the abnormal light shifted downward in the V direction by ½ pixel pitch with respect to the irradiation position of the ordinary light is one field. It will be irradiated alternately every time. Therefore, the spatial sampling area can be increased and the resolution can be improved.

This image pickup device that electrically shifts an image is more reliable than the image pickup device that mechanically shifts an image because there is no moving part that requires a complicated mechanical system. Can be increased and also
It can be manufactured with a simple structure.

[0015]

However, when the CCD image sensor is used for frame reading, the image pickup device for electrically performing the image shift is such that the exposure time required for picking up one image is six fields. Requires a fairly long exposure time.

For this reason, there is a problem in that the captured image is blurred when the movement of the subject is fast.

The exposure time can be shortened to the exposure time of four fields by providing a CCD image sensor having a so-called electronic shutter function and adjusting the exposure time by using this electronic shutter function. You can However, even if the exposure time is set to 4 fields by using the electronic shutter function, it is not possible to solve the problem of the blur of the captured image of the fast-moving subject.

The present invention has been made in view of the above problems, and in the case of using the image pickup means in frame reading, by shortening the exposure time of the image pickup means, a fast-moving subject can be obtained. It is an object of the present invention to provide an imaging device capable of performing high-resolution imaging without causing blur in a captured image.

[0019]

An image pickup apparatus according to the present invention comprises a first polarizing means for transmitting only the image pickup light of which polarization direction is one direction among the image pickup light, and the first polarizing means according to ON / OFF of a voltage. First rotation means for rotating the polarization direction of the imaging light from the polarization means, and emitting the imaging light from the first polarization means that has rotated this polarization direction; and imaging light from the first rotation means. Of the second polarization means, the second polarization means transmits only the imaging light having the polarization direction orthogonal to the polarization direction of the first polarization means, and the second polarization means in response to ON / OFF of the voltage. Second rotation means for rotating the polarization direction of the image pickup light, and emitting the image pickup light from the first polarization means having rotated the polarization direction, and the polarization direction of the image pickup light from the second rotation means. The optical path of the imaging light is shifted by a predetermined amount in accordance with The emits a predetermined amount shifted imaging light as the extraordinary light, also without shifting the optical path of the imaging light,
It has a birefringent means for emitting imaging light that does not shift the optical path as ordinary light, and a frame readout type imaging means for forming and outputting an imaging signal based on ordinary light or extraordinary light emitted from the birefringent means. The above-mentioned problem is solved by the feature.

The image pickup apparatus according to the present invention is the first image pickup apparatus described above.
The above problem is solved by having control means for controlling the rotating means by turning on and off the voltage for each field and controlling the second rotating means by turning on and off the voltage for each frame.

Further, in the image pickup device according to the present invention, the first and second polarizing means and the first and second rotating means are:
The first polarizing means and the first rotating means, which are respectively provided outside the imaging lens, are detachable, and the above-mentioned problems are solved.

[0022]

In the image pickup apparatus according to the present invention, when image pickup is started, the first polarizing means transmits only the image pickup light whose polarization direction is, for example, the horizontal (H) direction among the above-mentioned image pickup light. This H
The imaging light in the direction is incident on the first rotating means. The first rotating means polarizes the polarization direction of the image pickup light in the H direction in the vertical (V) direction when the voltage is off, and makes it enter the second polarizing means, and when the voltage is on, , The image pickup light in the H direction is directly transmitted and is incident on the second polarizing means. When the image pickup light in the H direction is incident from the first rotating unit, the second polarizing unit does not transmit it, and when the image pickup light in the V direction is incident from the first rotating unit, This is transmitted to irradiate the second rotating means. For example, when the voltage is turned on, the second rotating means irradiates the birefringence means with the image light in the V direction incident from the second polarizing means as it is, and when the voltage is turned off, the V direction is changed. The imaging light is converted into the imaging light in the H direction, and the birefringence means is irradiated with the imaging light. When the imaging light in the H direction is incident, the birefringence means irradiates the imaging means as ordinary light as it is without shifting the optical path of the imaging light in the H direction, and the imaging light in the V direction is incident. In this case, the optical path of the image pickup light in the V direction is shifted by a predetermined amount and the image pickup means is irradiated with the abnormal light. The image pickup means is a frame read-out type image pickup means, and forms and outputs an image pickup signal based on the ordinary light or the abnormal light emitted from the crystal plate.

Here, the control means controls the first liquid crystal plate by turning on and off the voltage for each field, and the second liquid crystal plate, for example, the first liquid crystal plate is first supplied with the voltage. The voltage is turned off for one frame at the timing of turning on, and the voltage is turned on and off so as to be turned on in the next frame.

As a result, in the first field after the start of image pickup, the voltage is turned on to the first rotating means, so that the image pickup light in the H direction is incident on the second polarizing means. Since the second polarizing means transmits only the imaging light in the V direction as described above, the imaging light is not irradiated on the imaging means in the first field.

Next, in the second field, the above first and second
Since the voltage is turned off to the rotating means, the imaging light in the V direction is emitted from the first rotating means, and the imaging light in the V direction is incident on the second rotating means via the second polarizing means. ,
The second rotating means converts the light into image light in the H direction and irradiates the birefringent means. The birefringence means is the H
The image pickup means is irradiated as ordinary light without shifting the optical path of the image pickup light in the direction. The image pickup means accumulates the charges related to the ordinary light in the second field. Of the charges relating to the ordinary light accumulated in the image pickup means in the second field, the even line charges are read out in the third field and output as an image pickup signal, and the odd line charges are read in the fourth field. It is output as an image pickup signal.

Next, since the voltage is turned on to the first rotating means in the third field, H is applied to the second polarizing means.
The imaging light in the direction is incident, and the imaging light is not emitted to the imaging means as in the first field.

Next, in the fourth field, since the voltage is turned off in the first rotating means and the voltage is turned on in the second rotating means, the imaging light in the V direction from the first rotating means. Is emitted, and the imaging light in the V direction is incident on the birefringent means via the second polarization means and the second rotation means. The birefringence means shifts the optical path of the imaging light in the V direction by a predetermined amount and irradiates the imaging means as abnormal light. The image pickup means accumulates charges relating to the abnormal light in the fourth field. Of the charges relating to the abnormal light accumulated in the image pickup means in the fourth field, the even line charges are read out in the fifth field and output as an image pickup signal, and the odd line charges are read in the sixth field. And output as an image pickup signal.

The image pickup signals output in the fourth field and the sixth field are formed by the ordinary light, and the image pickup signals output in the fifth field and the sixth field are in the optical path of the ordinary light. On the other hand, it is formed by extraordinary light having an optical path shifted by a predetermined amount. Therefore, an image formed from the image pickup signal relating to the ordinary light and the image pickup signal relating to the extraordinary light can have high resolution.

The time (exposure time) for irradiating the image pickup means with image pickup light (ordinary light or abnormal light) is the second field and the fourth field. Therefore, the substantial exposure time for performing the image shift processing as described above can be set to a total of three fields of the second field to the fourth field.

Further, by turning off the voltage to the first and second rotating means all the time, the H-direction image pickup light incident on the first rotating means via the first polarizing means is generated. The first rotating means converts the image light in the V direction into the image light, and the image light in the V direction is incident on the second rotating means through the second polarizing means, and the second rotating means It is converted into imaged light in the H direction, is incident on the birefringent means, and is made into ordinary light by this birefringent means. Then, only this ordinary light is constantly applied to the image pickup means. Therefore, the image pickup apparatus can be used as an image pickup apparatus that does not perform image shift.

Further, the voltage to the first rotating means is turned off all the time, and the voltage to the second rotating means is turned on and off, for example, for every one field, so that the image pickup means is set to 1
The above-mentioned ordinary light and extraordinary light can be emitted for each field. Therefore, the image pickup apparatus can be used as an image pickup apparatus that performs image shift.

Further, when the voltage to the first rotating means is turned off, the image pickup means (normal light or abnormal light)
When the voltage for the first rotating means is turned on, the image pickup light is not emitted to the image pickup means.
Therefore, by controlling the timing of turning off the voltage to the first rotating means, the image pickup device can be used as an image pickup device having a shutter function.

In the image pickup device according to the present invention, the first and second polarization means and the first and second rotation means are:
Each of the first polarization means and the first rotation means is detachable in addition to being provided outside the imaging lens.

Therefore, when the first polarizing means and the first rotating means are removed, the image pickup device can be used as an image pickup device for performing image shift and an image pickup device for not performing image shift. First polarizing means and first
When the rotating unit is attached, the image pickup apparatus can be used as an image pickup apparatus that shifts an image in the exposure time of the three fields and an image pickup apparatus having the shutter function.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an image pickup apparatus according to the present invention will be described below with reference to the drawings.

The image pickup apparatus of the embodiment according to the present invention, as shown in FIG. 1, only the image pickup light whose polarization direction is, for example, the horizontal (H) direction (hereinafter, simply referred to as the H direction image pickup light) in the image pickup light. For example, when the voltage is turned on, the first polarizing plate (first polarizing means) 1 for transmitting the image light in the H direction is directly transmitted, and when the voltage is turned off, the image light in the H direction is polarized. Is converted into image light in the vertical (V) direction (hereinafter, simply referred to as image light in the V direction) and emitted, and the first twisted-matic liquid crystal plate (first rotation means) 2 and the first Of the imaging light from the liquid crystal plate 2, a second polarizing plate (second polarizing means) that transmits only the imaging light of the imaging light in the V direction.
3 and, for example, when the voltage is turned on, the V direction imaging light from the second polarizing plate 3 is transmitted as it is, and when the voltage is turned off, the V direction imaging light is converted into the H direction imaging light. And a twisted-matic second liquid crystal plate (second rotating means) 4 for emitting the light.

In the image pickup device, the image pickup lens 5 that converges and emits the image pickup light in the H direction or the V direction from the second liquid crystal plate 4, and the H direction or the V direction from the image pickup lens 5. When an infrared cut filter (IR filter) 6 that removes an infrared component from the image pickup light and emits the image pickup light, and the image pickup light in the V direction is incident through the IR filter 6,
When the optical path of the imaging light in the V direction is shifted by a predetermined amount (for example, 1/2 pixel pitch) and emitted as abnormal light, and the imaging light in the H direction is incident, the optical path of the imaging light in the H direction is shifted. It has a crystal plate (birefringence means) 7 that directly emits ordinary light without doing so.

In the image pickup device, the phase difference plate 8 which circularly polarizes and outputs the ordinary light and the extraordinary light incident from the crystal plate 7, the optical low-pass filter (LPF) 9, and the ordinary light from the optical LPF 9. Alternatively, a CCD image sensor (image pickup means) 10 for forming an image pickup signal related to the ordinary light and photoelectrically converting the received abnormal light to form an image pickup signal related to the abnormal light, and the first and second liquid crystals. Liquid crystal control circuit (control means) for turning on and off the voltage applied to the plates 2 and 5
11 and 11.

As the CCD image sensor 10, a so-called frame reading type CCD image sensor is provided.

Next, the operation of the image pickup apparatus according to this embodiment having such a configuration will be described.

In the image pickup apparatus according to this embodiment shown in FIG. 1, when image pickup is started, image pickup light is incident on the first polarizing plate 1.

Of the image pickup light, the first polarizing plate 1 transmits only the image pickup light whose polarization direction is the H direction. This H
The imaging light in the direction is incident on the first liquid crystal plate 2.

The voltage applied to the first liquid crystal plate 2 is
The liquid crystal control circuit 11 turns on / off every field as shown in FIG. Therefore, the first
The imaging light in the H direction incident on the liquid crystal plate 2 of FIG.
The first field between time t1 and time t2 in (a),
The third field between time t3 and time t4, time t5
... between the time t6 and the fifth field, the image is directly incident on the second polarizing plate 3 as H-direction imaging light, and the second field is between the time t2 and the time t3 in FIG. In the fourth field between time t4 and time t5, the sixth field between time t6 and time t7, etc., the polarization direction is converted into V-direction imaging light and incident on the second polarizing plate 3. To be done.

The second polarizing plate 3 transmits only the image pickup light whose polarization direction is the V direction. Therefore, the imaging light in the V direction that is incident on the even-numbered fields of the second, fourth, and sixth fields is transmitted through the second polarizing plate 3. Also,
The image pickup light in the H direction incident on the odd-numbered fields of the first, third and fifth fields is not transmitted. This second
The imaging light in the V direction transmitted through the polarizing plate 3 of
Is incident on the liquid crystal plate 4.

The voltage applied to the second liquid crystal plate 4 is
The liquid crystal control circuit 11 causes the times t1 to t1 in FIG.
The voltage is turned off in the first frame between time t3 and time t3.
The voltage is turned on and off for each frame such that the voltage is turned on in the second frame at time t5. When the voltage is turned off, the second liquid crystal plate 4 emits the incident imaging light as it is without rotating the polarization direction of the imaging light.
When the voltage is turned on, the polarization direction of the incident imaging light is rotated and emitted.

Therefore, the second field is the second field.
Since the voltage applied to the liquid crystal plate 4 is turned off, the polarization direction of the imaging light in the V direction which is incident on the second liquid crystal plate 4 in the second field is changed by the second liquid crystal plate 4. It is rotated and enters the imaging lens 5 as imaging light in the H direction.

Further, since the voltage to the second liquid crystal plate 4 is turned on in the fourth field, the image pickup light in the V direction incident on the second liquid crystal plate 4 in the fourth field is generated. Then, the light passes through the second liquid crystal plate 4 as it is and enters the imaging lens 5.

The image pickup lens 5 converges the image pickup light in the H direction and the image pickup light in the V direction, and makes this incident on the IR filter 6. The IR filter 6 removes infrared components from the H-direction imaging light and the V-direction imaging light,
This is incident on the crystal plate 7.

When the image pickup light in the V direction is incident, the crystal plate 7 shifts its optical path by, for example, 1/2 pixel pitch, and the image pickup light in the V direction obtained by shifting the optical path is regarded as extraordinary light. It is incident on 8. Further, when the image pickup light in the H direction is incident, the image pickup light in the V direction that does not shift the optical path is incident on the phase difference plate 8 as ordinary light.

The retardation plate 8 circularly polarizes the ordinary light and the extraordinary light, and irradiates the CCD image sensor 10 with this through the optical LPF 9.

Accordingly, the CCD image sensor 10 is irradiated with the ordinary light in the second field and the
The abnormal light is emitted to the field eyes.

The CCD image sensor 10 is the same as the CCD image sensor 2 described above.
Charges are accumulated as shown between time t2 and time t3 in FIG. 2 (e) according to the ordinary light radiated to the field eyes, and the charges of the even (Odd) line among these charges are shown in FIG. 2 (c). By the Odd readout pulse shown at time t3, the readout is performed over one field from time t3 to time t4 in FIG. 7G (readout in the third field), and this is an image pickup signal not shown as an Odd image pickup signal without shift. Supply to the processing circuit. Further, the electric charge of the odd line (Even) is set to 1 between the time t4 and the time t5 in the same figure (h) by the even read pulse shown at the time t4 in FIG. 2 (d).
Field reading is performed (reading in the fourth field), and this is supplied to the above-mentioned image pickup signal processing circuit as an image signal for shift-free Even.

Further, the CCD image sensor 10 is
Depending on the extraordinary light emitted in the fourth field, FIG.
Charges are accumulated as shown from time t4 to time t5 in (f), and the charges in the Odd line of this charge are read by the Odd read pulse at time t5 in FIG. ) Is read over one field from time t5 to time t6 (read in the fifth field), and this is supplied to an image pickup signal processing circuit (not shown) as a shift-added Odd image pickup signal. Further, the charge of the odd (Even) line is set to 1 between the time t6 and the time t7 in FIG. 2 (j) by the even read pulse shown at the time t6 in FIG. 2 (d).
Field reading is performed (reading in the sixth field), and this is supplied to the imaging signal processing circuit as an even imaging signal for shift.

The imaging signal processing circuit forms an imaging signal for one field (non-shifting field imaging signal) from the unshifted Odd imaging signal and the unshifted Even imaging signal, and also shifts the Odd imaging signal. And an image pickup signal for one field from the image pickup signal for Even with shift (field image pickup signal with shift)
To form. Then, the field image signal without shift and the field image signal with shift are supplied to, for example, a monitor device (not shown).

The field image signal without shift is formed based on the ordinary light, and the field image signal with shift is formed based on the extraordinary light. For this reason, the field image signal with shift is shifted by 1/2 pixel pitch with respect to the field image signal without shift. Therefore, a display image for one frame can be displayed on the monitor device by the image signal of the unshifted one field (field image signal without shift) and the image signal of the shifted one field (field image signal with shift). As a result, a high-resolution display image relating to an image pickup signal with an increased spatial sampling area can be formed on the monitor device.

On the other hand, in order to perform such an image shift process, it is necessary to form the field image signal without shift and the field image signal with shift, but the field image signal without shift is in the second field. It is formed by irradiating the CCD image sensor 10 with imaging light (ordinary light), and the field image signal with shift is formed by irradiating the CCD image sensor 10 with imaging light (abnormal light) in the fourth field. To be done.

Therefore, in the image pickup apparatus according to the present embodiment, the exposure time for the total of three fields of the second field to the fourth field is one image (1
It is possible to form an image pickup signal for each frame.

Therefore, when a fast-moving subject is imaged, one image can be imaged within the exposure time of the three fields, and a high-resolution display image without blurring can be obtained.

There is a problem that the liquid crystal plate maintains the characteristics when the voltage is on for a while even after the voltage is turned off (the reaction when the voltage is off is slow). This becomes remarkable as the voltage is turned on for a long time.

However, since the voltage is turned on and off in the first liquid crystal plate 2 at a short interval of every one field, the time for maintaining the characteristics when the voltage is turned on does not affect the exposure time. Further, the second liquid crystal plate 4 is
The voltage is turned on and off for each frame, but even if the characteristics when the voltage is turned on are maintained when the voltage is turned off as shown by the diagonal lines in FIG. 2B, the characteristics when the voltage is turned on are maintained. The time for which the image pickup means is not irradiated with the image pickup light is (time t1 to time t2, time t5 to time t6).
..), the exposure time is not affected.

Therefore, the first and second liquid crystal plates 2 and 4 are
As a result, an inexpensive liquid crystal plate can be provided, which can contribute to cost reduction of the imaging device.

Next, the image pickup apparatus according to the present embodiment can open the shutter a plurality of times, for example, within one field by controlling the application time of the voltage to the first liquid crystal plate 2.

That is, when the shutter is released three times within one field, the liquid crystal control circuit 11 operates as shown in FIG.
In the second field from time t11 to time t16 in (a), the voltage to the first liquid crystal plate 2 is turned off from time t11 to time t12 in FIG.
It is turned on during 13 and turned off between time t13 and time t14,
It is turned on from time t14 to time t15, and turned off from time t15 to time t16.

The liquid crystal control circuit 11 is similar to that shown in FIG.
In the first frame shown at time t10 to time t16 in (b), the voltage to the second liquid crystal plate 4 is turned off.

As a result, the voltage to the first liquid crystal plate 2 is turned on between the times t12 and t13 and the time t14.
Between t15 and t15, the image pickup light in the H direction which is incident on the first liquid crystal plate 2 through the first polarizing plate 1 is transmitted through the first liquid crystal plate 2 with the polarization direction being unchanged. ,
It does not pass through the second polarizing plate 3 that transmits only the image pickup light whose polarization direction is the V direction. Therefore, the time t1
During the period from 2 to t13 and from the time t14 to t15, the above CCD is used.
The image sensor 10 is not irradiated with imaging light.

Further, during the time t11 to t12 when the voltage to the first liquid crystal plate 2 is turned off, and the time t13 to t14.
Between the time t15 and the time t16, the image light in the H direction incident on the first liquid crystal plate 2 via the first polarizing plate 1 is emitted by the first liquid crystal plate 2 in the V direction. The image pickup light is incident on the second polarizing plate 3, is transmitted through the second polarizing plate 3, and is incident on the second liquid crystal plate 4. As described above, the second liquid crystal plate 4 has the time t10 to the time t.
Since the voltage is turned off during one frame of 16, the image pickup light in the V direction is made into the image pickup light in the polarization direction H and is incident on the crystal plate 7 via the IR filter 6. The crystal plate 7 irradiates the CCD image sensor 10 through the phase difference plate 8 and the optical LPF 9 as ordinary light without shifting the optical path of the image pickup light in the H direction.

That is, the CCD image sensor 10
In the second field, the time t11
Between t12, time t13 to t14, and time t15.
The above-mentioned ordinary light is irradiated in three times during t16. In other words, the shutter is released three times during one field.

The CCD image sensor 10 has the above-mentioned 3
The ordinary light that is emitted in a divided manner is received to accumulate charges as shown at time t11 to time t16 in FIG. 3E, and the charges in the Odd line among the accumulated charges are shown in FIG. 3C.
1 field is read by the Odd read pulse shown at time t16 of FIG.
It is supplied to the imaging signal processing circuit as an imaging signal for Odd without shift as shown from 6 to t17. Also, Ev
Ev showing the charge of the en line at time t17 in FIG.
One field is read by the en read pulse, and this is supplied to the above-mentioned image pickup signal processing circuit as a shiftless Odd image pickup signal as shown from time t17 to time t22 in FIG.

The liquid crystal control circuit 11 is similar to that shown in FIG.
In the fourth field from time t17 to time t22 in (a), the voltage to the first liquid crystal plate 2 is turned off from time t17 to time t18 in FIG.
It is turned on during 19 and turned off between time t19 and time t20,
It is turned on from time t20 to time t21 and turned off from time t21 to time t22.

The liquid crystal control circuit 11 is similar to that shown in FIG.
In the second frame from time t16 to time t22 in (b), the voltage to the second liquid crystal plate 4 is turned on.

As a result, the voltage to the first liquid crystal plate 2 is turned on between the times t18 and t19 and the time t20.
Between t21 and t21, the image pickup light in the H direction that is incident on the first liquid crystal plate 2 through the first polarizing plate 1 is transmitted through the first liquid crystal plate 2 without changing the polarization direction. ,
It does not pass through the second polarizing plate 3 that transmits only the image pickup light whose polarization direction is the V direction. Therefore, the time t1
During the period from 8 to t19 and the time from t20 to t21, the above CCD is used.
The image sensor 10 is not irradiated with imaging light.

Further, during the time t17 to t18 when the voltage to the first liquid crystal plate 2 is turned off, and the time t19 to t20.
Between the time t21 and the time t22, the image light in the H direction incident on the first liquid crystal plate 2 through the first polarizing plate 1 is emitted by the first liquid crystal plate 2 in the V direction. The image pickup light is incident on the second polarizing plate 3, is transmitted through the second polarizing plate 3, and is incident on the second liquid crystal plate 4. As described above, the second liquid crystal plate 4 has the time t16 to the time t.
Since the voltage is turned on during one frame of 22, the imaging light in the V direction is directly incident on the crystal plate 7 via the IR filter 6. The crystal plate 7 shifts the optical path of the imaging light in the V direction by 1/2 pixel pitch, and irradiates the CCD image sensor 10 with this as abnormal light via the phase difference plate 8 and the optical LPF 9.

That is, the CCD image sensor 10
In the fourth field, from time t17
Between t18, time t19 to t20, and time t21.
The above-mentioned abnormal light is emitted in three times during t22. In other words, the shutter is released three times during one field.

The CCD image sensor 10 has the above-mentioned 3
The extraordinary light that is emitted in a divided manner is received to accumulate charges as shown from time t17 to time t22 in FIG.
Of the accumulated charges, the charges on the Odd line are read over one field by the Odd read pulse shown at time t22 in the same figure (c), and this is shifted as shown from time t22 to time t23 in the same figure (i). Provided to the image pickup signal processing circuit as an Odd image pickup signal. Further, the electric charge of the Even line is read over one field by the Even read pulse shown at time t23 in FIG. 3D, and this is read from time t23 to time t2 in FIG.
It is supplied to the image pickup signal processing circuit as an image pickup signal for Odd without shift as shown in FIG.

The image pickup signal processing circuit includes the image pickup signal for Odd without shift, the image pickup signal for Even without shift, the image pickup signal for Odd with shift, and the Ev with shift.
Based on the en image signal, the high-resolution image signal is formed as described above, and this is supplied to the monitor device.

As described above, the image pickup apparatus according to the present embodiment is
By controlling the timing of turning off the voltage to the first liquid crystal plate 2 a plurality of times during one field, for example, the shutter can be released a plurality of times within one field.

Further, the voltage to the first liquid crystal plate 2 is controlled to be turned off only once in one field, and the timing to turn off the voltage only once is the timing at which the Odd read pulse is supplied. A desired shutter speed can be realized by back-calculating from and setting.

Next, in the image pickup apparatus according to the present embodiment, the first polarizing plate 1 and the first liquid crystal plate 2 which are surrounded by a dotted line in FIG. 1 are detachable.

Therefore, when the first polarizing plate 1 and the first liquid crystal plate 2 are detached and used, the voltage to the second liquid crystal plate 4 is turned on all the time or turned off all the time. It can be used as an imaging device that does not perform the above-mentioned image shift. Further, by controlling the voltage to the second liquid crystal plate 4 on and off, for example, for each field, the CCD image sensor 10 can be irradiated with ordinary light or abnormal light for each field, and the image shift can be performed. It can be used as an image pickup device.

When the first polarizing plate 1 and the first liquid crystal plate 2 are attached and used, the image pickup apparatus is used as an image pickup apparatus that does not perform the image shift and an image pickup apparatus that performs the image shift. In addition, as described above, the image pickup device can be used as an image pickup device that shifts an image with an exposure time of three fields and an image pickup device having the shutter function.

Therefore, it is possible to properly use each of the above-mentioned functions according to the subject to be imaged.

Further, an existing image pickup device for shifting an image is constructed by removing the first polarizing plate 1 and the first liquid crystal plate 2, that is, the second polarizing plate 3 to the CCD image sensor 10. ing. For this reason, the first polarizing plate 1 and the first liquid crystal plate 2 which are detachable are only provided in the preceding stage of the second polarizing plate 3 without changing the optical system of the existing image pickup device. It is possible to configure an imaging device that can obtain the above effects with a simple configuration. Therefore, the imaging device can be manufactured at low cost.

Further, the second polarizing plate 3 and the second liquid crystal plate 4 are required to perform the image shift, and the first polarizing plate 1, the first polarizing plate 1 and the first liquid crystal plate 4 are required to provide the shutter function. The liquid crystal plate 2 and the second liquid crystal plate 3 are required, but the first polarizing plate 1 and the first liquid crystal plate 2 are provided in front of the second polarizing plate 3 as in this imaging device. By providing the second polarizing plate 3, the second polarizing plate 3 can be shared during the image shift and the shutter function use. Therefore, the polarizing plate 1
The material cost for one sheet can be saved, and the above cost reduction can be achieved.

[0084]

As is apparent from the above description, the image pickup apparatus according to the present invention can set the substantial exposure time for one image when performing image shift to three fields. Therefore, even if the subject moves fast, it is possible to obtain a high-resolution captured image without blurring.

An image pickup device which does not perform image shift depending on how the voltage to the first and second polarization means is turned on and off,
It can be used as an image pickup device for performing image shift, an image pickup device for performing image shift with an exposure time of three fields, and an image pickup device having a sitter function. Therefore, it is possible to properly use each of the above functions according to the subject.

Further, since the first polarizing means and the first rotating means are detachable, it is only necessary to attach the first polarizing means and the first rotating means to an existing image pickup device for image shifting. With such a simple configuration, it is possible to realize the image pickup apparatus having the above four functions.

When a liquid crystal plate is provided as the first and second rotating means, the liquid crystal plate maintains the characteristics when the voltage is turned on for a while even after the voltage is turned off (reaction when the voltage is turned off). There is a problem. This becomes remarkable as the voltage is turned on for a long time.

However, since the voltage is turned on and off in the first rotating means at a short interval of every one field, the time for maintaining the characteristic when the voltage is turned on does not affect the exposure time. Also, the second rotating means is
The voltage is turned on and off for each frame, but even if the above voltage-on characteristics are maintained when the voltage is turned off,
Since the time for maintaining the characteristics when the voltage is on is within the time when the imaging light is not applied to the imaging means, it does not affect the exposure time. Therefore, even if an inexpensive liquid crystal plate is provided as the first and second rotating means, the above effect can be achieved. Therefore, since the inexpensive liquid crystal plate is provided, the imaging device can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an image pickup apparatus according to the present invention.

FIG. 2 is a time chart for explaining the operation of the image pickup apparatus of the above-described embodiment when performing image shift with an exposure time of 3 fields.

FIG. 3 is a time chart for explaining a shutter function of the image pickup apparatus of the above embodiment.

[Explanation of symbols]

1-First polarizing plate 2-First liquid crystal plate 3-Second polarizing plate 4・ ・ ・ ・ ・ ・ ・ ・ Second liquid crystal plate 5 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Imaging lens 6 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Infrared cut filter (IR filter) 7 ・ ・ ・ ・··· Crystal plate 8 ··· Phase retarder 9 ··· Optical low-pass filter (LP
F) 10 ・ ・ ・ ・ ・ ・ CCD image sensor 11 ・ ・ ・ ・ ・ ・ ・ ・ Liquid crystal control circuit

Claims (3)

[Claims] 1. A first polarization means for transmitting only the imaging light having one polarization direction among the imaging light, and rotating the polarization direction of the imaging light from the first polarization means in response to ON / OFF of a voltage. Of the imaging light from the first rotating means that emits the imaging light from the first polarizing means that rotates the polarization direction, and the polarization direction of the imaging light from the first rotating means,
The second polarization means for transmitting only the imaging light in the polarization direction orthogonal to the polarization direction of the first polarization means, and the polarization direction of the imaging light from the second polarization means according to the on / off of the voltage. Second rotating means for rotating and rotating the polarization direction to emit the imaged light from the first polarizing means; and, depending on the polarization direction of the imaged light from the second rotating means,
The optical path of the image pickup light is shifted by a predetermined amount, the image pickup light obtained by shifting the optical path by a predetermined amount is emitted as abnormal light, and the image pickup light that is not shifted in the optical path of the image pickup light is emitted as ordinary light. An image pickup apparatus, comprising: a birefringent unit that performs the above-described birefringent unit; 2. A control means for controlling the first rotating means by turning on / off the voltage for each field and controlling the second rotating means by turning on / off the voltage for each frame. The image pickup apparatus according to claim 1. 3. The first and second polarization means and the first and second rotation means are respectively provided outside an imaging lens, and the first polarization means and the first rotation means are The image pickup apparatus according to claim 1, wherein the image pickup apparatus is detachable.